OFFSHORE GRID “SUPERGRID” INTERCONNECTION REGULATION

1. Introduction

An offshore electricity supergrid is a coordinated network linking multiple offshore wind farms, coastal transmission systems and international interconnectors through shared offshore transmission infrastructure. Unlike traditional radial connections, a supergrid can permit electricity to flow between several countries and markets, increasing flexibility and reducing dependence on individual transmission routes.

In the UK, regulation is evolving from separate point-to-point offshore connections toward coordinated offshore transmission and multi-purpose interconnection. Ofgem's Offshore Transmission Network Review has classified offshore assets into radial and non-radial categories, while its current framework addresses Multi-Purpose Interconnectors (MPIs) and other offshore hybrid assets.

2. Legislative and Regulatory Framework

The Electricity Act 1989 provides the principal statutory framework for electricity generation and transmission licensing. Offshore transmission is separately recognised within the Act, and offshore transmission systems require appropriate licensing arrangements.

Ofgem regulates electricity interconnectors through licensing and, for relevant projects, the cap-and-floor regime. The regime seeks to balance investment incentives with consumer protection. Ofgem has also stated that future interconnector planning should be integrated with strategic network planning rather than being treated exclusively as individual projects.

3. Multi-Purpose Interconnectors

A major development is the Multi-Purpose Interconnector, which can simultaneously connect offshore generation to the UK and provide cross-border interconnection.

This creates a hybrid legal problem because the same infrastructure may perform both offshore transmission and international interconnection functions. Regulation therefore has to address licensing, charging, ownership, market access, balancing, curtailment and allocation of transmission capacity.

In March 2026, Ofgem announced that the Government and Ofgem were pursuing Offshore Bidding Zones with implicit trading arrangements as the preferred market model for future MPIs. The decision also identifies continuing regulatory issues involving revenue risks, Contracts for Difference arrangements, curtailment and balancing.

4. Network Planning and Coordination

A supergrid requires coordinated planning across multiple jurisdictions. Regulators must determine:

who owns offshore transmission assets;

who operates interconnected networks;

how construction costs are allocated;

how cross-border capacity is auctioned;

how congestion is managed;

how offshore wind receives market access;

how outages and emergency events are handled; and

how environmental impacts are assessed cumulatively.

Ofgem's Offshore Transmission Network Review was specifically designed to increase coordination between offshore transmission and interconnection.

5. Case Law – Sustainable Shetland v Scottish Ministers

Case Name/Citation: Sustainable Shetland v The Scottish Ministers and Another [2015] UKSC 4.

Facts: Scottish Ministers granted section 36 consent for a large wind-farm development in Shetland. The project included extensive associated infrastructure, and environmental groups challenged the decision concerning impacts on protected migratory birds.

Legal Issue: Whether the Ministers had lawfully considered the relevant environmental obligations when deciding whether to grant electricity-generation consent.

Judgment: The Supreme Court unanimously dismissed the appeal and upheld the Ministers' decision.

Legal Principle/Ratio Decidendi: Major energy infrastructure decisions must properly consider material environmental considerations and applicable statutory obligations.

Significance: For a supergrid, environmental assessment cannot be limited to individual turbines. The cumulative effects of offshore cables, substations, interconnectors and associated infrastructure may need consideration.

6. Case Law – Redcar & Cleveland Borough Council v Secretary of State

Case Name/Citation: R (Redcar & Cleveland Borough Council) v Secretary of State for Business, Enterprise and Regulatory Reform [2008] EWHC 1847 (Admin).

Facts: The Council challenged a section 36 consent for an offshore wind farm near Redcar.

Legal Issue: The case considered the statutory meaning of a “generating station”, procedural issues and whether the Secretary of State had lawfully exercised discretion in relation to the offshore project.

Judgment: The substantive challenge was dismissed and the consent remained effective.

Legal Principle/Ratio Decidendi: Statutory powers concerning offshore electricity infrastructure must be interpreted according to the statutory framework, while decision-makers retain legally structured discretion concerning project approval and procedure.

Significance: The case illustrates the importance of accurately defining the regulatory boundary between generation, transmission and associated offshore infrastructure—a particularly significant issue where a supergrid combines these functions.

7. Regulatory Evolution

The UK's regulatory approach is moving from conventional radial offshore connections toward integrated offshore networks. Ofgem's 2024 Offshore Hybrid Asset framework created a specific regime for non-standard interconnectors, recognising that hybrid assets have a different risk profile from traditional point-to-point interconnectors.

The 2026 strategic approach now expressly considers both conventional interconnectors and Offshore Hybrid Assets, including MPIs and non-standard interconnectors.

8. Conclusion

Offshore supergrid regulation represents a shift from isolated project regulation toward whole-system, cross-border network governance. The legal framework must integrate electricity licensing, offshore transmission regulation, interconnector rules, market arrangements, environmental assessment and strategic network planning. UK regulatory developments concerning MPIs and offshore hybrid assets demonstrate an evolving framework designed to accommodate offshore wind expansion while maintaining system reliability, competition, investment certainty and consumer protection.